The present invention relates to a roller press of the kind (hereinafter referred to as of the kind described) comprising two rollers which have a variable nip width and which are driven in opposite rotational directions via two reduction gear units each of which is mounted on a separate shaft for a respective one of the rollers, the gear units having a torque reaction system,
In known roller presses of the above kind, each gear unit is normally connected to the foundation or the machine frame by means of a single torque arm. This, however, involves the disadvantage that the torques are transformed into reaction forces, causing high loads in the gear unit bearings and bending of the roller shafts.
Therefore, owing to the significant torques and torque variations generally occurring in roller presses, it is advantageous to utilize a dual arm reaction system with the capability of directly balancing the torques without generating reaction forces causing high loads in the bearings.
A roller press of the this kind is known from EP-A-0280897 where the torques occurring in the two gear units are substantially balanced against each other, so that any differential torque, arising as a result of a numerical difference between the two torques, is absorbed by a single torque arm fixed between one gear unit and the foundation or the machine frame of the roller press. This reaction system is of a relatively complex construction in that it requires a torsion shaft, supported by bearings on the fixed gear unit, and pivotally connected at each end to a coupling means, which in turn is connected to the movable gear unit. Each coupling means for the displaceable gear unit is connected to the torsion shaft by means of a coupling arm so that the torque from the displaceable gear unit produces oppositely-directed torsion of the torsion shaft. As a consequence thereof, the system is relatively expensive, both in terms of manufacture and maintenance. Another inherent weakness of that system is the need for an additional torque arm which is attached to the foundation or the machine frame in order to absorb a potential differential torque arising as a result of a difference in torques in the two gear units.
It is the object of the invention to provide a reaction system for a roller press of the kind described whereby the need for a torque absorption mechanism attached to the machine frame is eliminated, with the added benefit that the system is simple and cheap to manufacture and maintain in comparison with the known system.